Human-body communication is a technique for transmitting signals between apparatus connected to a human body by using the human body having conductivity as a communication channel. In the human-body communication technique, a communication network to various portable apparatuses such as personal digital assistants (PDAs), portable personal computers, digital cameras, MP3 players, and mobile phones or a communication network to fixed-type apparatuses such as printers, TVs, and entrance systems can be implemented by a user simply contacting the apparatuses.
An existing human-body communication methods, there have been proposed a method using a limited passband, a method using scrambling with user's unique ID, a method of using channel coding, a method using interleaving, a method using spreading, and the like.
In the existing human-body communication method, a passband having a central frequency fc which is used for most communication systems needs to be used in order to use the limited frequency band. Therefore, a digital-to-analog converter, an analog-to-digital converter, a central frequency converter, and the like needs to be provided to analog transmission and reception stages. Accordingly, the existing human-body communication methods have a problem in terms of low power consumption.
In addition, recently, a human-body communication method using a time-domain/frequency-domain spreading scheme for increasing a processing gain has been proposed. However, due to a limited frequency band, the human-body communication method has a problem in terms of increase in transmission data rate and efficiency of stable data communication.